The invention relates to a device for changing the height of rolls in rolling stands and for carrying out a roll change. This device uses a wedge adjusting device for bringing the lower work roll into line with a rolling line. The device comprises an adjusting wedge, which can be displaced in the longitudinal direction of the rolls and has a continuously planar wedge surface area. A displacing device is connected to the adjusting wedge. A clamping device fixes the adjusting wedge. A roll changing device changes the rolls. That device can be moved in the longitudinal direction of the rolls. The rolls are supported at their ends in roll chocks and are guided with adjustable height in stand uprights arranged in parallel. Each of the two roll chocks is supported in the stand upright by means of an upper pressure plate, the adjusting wedge and a lower pressure plate.
It is known to bring the upper edge of the lower work roll into line with the rolling line by means of adjusting plates of different heights, which are chosen according to the respective degree of compensation. These plates are moved in and out together with the chocks from a roll changing carriage. A major disadvantage is that, for each degree of compensation, a pair of these adjusting plates must be kept on standby, their handling is difficult and it is only possible to bring the lower work roll into line with the rolling line within the range of graduation of the adjusting plate thickness.
EP 0 513 946 A2 already discloses a wedge adjusting device for bringing the upper edge of the lower work roll into line with the rolling line. Two respectively interacting wedges are formed in a step-shaped manner and form horizontal supporting faces, which determine the position of the lower work roll in relation to the rolling line by the displacement position assumed by the wedges. With such a stepped wedge, however, stepless adjustment of the work roll to the rolling line cannot be achieved, but rather only an approximate approach to the rolling line is possible, dependent on the step height. The lower wedges are connected by means of traction elements and are equipped with a motorized adjusting drive. The upper wedge elements are fixed in cross members, on which the chocks of the rolls are supported. To adapt the work rolls to the rolling line, each of the cross members is raised by four pressure-medium cylinders in each case, and the lower wedge elements are correspondingly displaced horizontally. This adjusting operation consequently requires the complex use of many adjusting devices together. For the roll change, the chocks are assigned wheelsets, which can be lowered onto lateral guide rails, arranged alongside the large-area cross members, and can then be moved out in the axial direction of the rolls. The lowering movement takes place by means of the wedge adjustment. A particular disadvantage of this structural design is the larger structural width of the devices within the roll stand.
DE 25 13 666 A1 likewise discloses a rolling stand in which the chocks carrying work rolls and back-up rolls are assigned running wheels. The chocks can consequently be lowered on guide rails and moved out of and into the roll stand in the axial direction of the rolls. For positioning the lower work roll onto the rolling line, a wedge adjusting device is provided, comprising two wedges acting in opposite directions and having assigned drive spindles. Arranged laterally next to the adjusting wedges on both sides are lifting cylinders, with which the chocks can be raised for actuating the wedge adjusting device and can be released after lowering, so that the chocks are supported in the stand frame exclusively by means of the wedge adjusting device. This embodiment also requires a relatively large installation width.
The solution known from EP 0 231 445 A1 also uses the principle of stepped plates for an approximate adjustment of the work roll in relation to the rolling line, in that stepped plates of different heights are arranged in a displacement frame and, after raising of the roll chocks by means of a lifting cylinder, can be positioned under them. Stepless fine adjustment takes place by means of a wedge arrangement, which comprises two wedges engaging in each other, the lower wedge being displaced by a horizontally acting adjusting cylinder and the second wedge, resting on the first, and consequently the stepped plates, being raised vertically. According to a further embodiment, the stepped plate arrangement is reduced to a stepped plate with only one height, so that a selective approximate adjustment is only possible by manually changing the stepped plate. The two wedge adjusting devices and the lifting cylinders are structurally integrated in the roll changing carriages and are displaced together with the roll changing carriage during a roll change. A major disadvantage of this structural design is the provision of two independent adjusting devices, whereby the overall structural height of the roll changing device increases.
JP 07-265919 A discloses a wedge adjusting device with an adjusting wedge with two planar wedge surface areas for adjusting the lower work roll to the adjustment line. A roll changing device is not described or shown, and so this document also does not disclose any information regarding any structural and functional interaction of these components.
It is also the case with the device known from DE 28 06 525 A1 for bringing the upper edge of the lower work rolls into line with the rolling line that adjusting pieces of different heights that are kept in a displacement frame are selectively pushed under the roll chocks after said roll chocks have been raised. This solution once again does not allow the work roll contour to be steplessly made to approach the rolling line. The displacement frame for the adjusting pieces is arranged displaceably on the moving-out carriage for the set of rolls. The lifting devices for the roll chocks are also integrated in the moving-out carriages.